@WayOutWestMom can help with the medical school questions. My understanding is that all medical schools combined admit only about 25 international students each year.
Your plan is extremely ambitious, and full of what are very, very far-fetched long shots. For one thing, your odds of even getting accepted as an international student at the universities you tagged are about 1%. Your odds of getting a full scholarship are less than that. Harvard is need blind and meets full need, but it is about as competitive as it gets in terms of college admissions. Emory is need blind, but won’t meet full need for international students. A 1340 is extremely low for many engineering programs, although you can apply test optional this year.
There is no such thing as a “pre-med major”. Biology is common, but not necessary. You must take (and do excellent in) the undergrad classes that medical schools require and then you take the MCAT exam. You can major in anything while doing so. However, given that engineering has a fairly long list of requirements, doesn’t overlap all that much with the med requirements, and doesn’t leave room for many electives, it is not realistic to major in engineering AND fit in your med school requirements in four years. It can be done with additional semesters of undergrad, but your scholarship certainly won’t pay for that, nor, if you plan on med school, would you want to spend more years in undergrad than you have to. Also, a 3.0 is a good grade for engineering classes, but terrible if one plans to apply to medical school.
I don’t know of many jobs for astrophysicists that don’t require citizenship and a security clearance, but you might be able to find something in your own country (teaching, working for private company, etc.).